I dunno! It's up to you! I don't really think the "Adventurer's Guild" as a concept belongs to anyone in particular, so if you want to adapt it into something else or start something similar, it would be entirely up to you!
All of the above!
I do like the idea that some islands have different interpretations on the subject.
I'm actually not quite sure if there are any "empire-wide" laws on SA, given that in my headcanon the Queen herself doesn't legislate. To use the United States as a comparison, for my headcanon SA has almost no federal government. Each state has their own things and they try to bully/pressure each other into passing various laws, but ultimately each island decides their own laws.
I would be okay with it if you want to be mean to Gawrgaru!
My main request would be to please not release Ume. My current plan is to keep her with him for a while.
The other thing to keep in mind that Gawrgaru isn't framed as an antagonist in my story. If you're too mean to him, your character might end up described as a bully.